This is a continuing study of motor control systems that has concentrated on the motor cortex and the pyramidal pathway. Currently our research is focused upon fusimotor innervation of the muscle spindle. We are studying the nature of fusimotor innervation in primate spindles. This is a study designed to establish a foundation for further analyses of primate motor control systems. We are initiating a study of spindle afferent projections from ankle flexor and extensor muscle to the primary motor cortex and to Area 3A. In this study the discharge characteristics of cortical neurons during ramp stretches of varying rates and lengths will be analyzed and compared to the discharge characteristics of primary and secondary muscle afferents during the same ramp stretches. This study promises to give us an understanding of what information is fed back to the cortex and to some degree how the information is translated within the cortex.